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Principal characteristics of the rock scallop The purple-hinge rock scallop has strong potential to become a substantial figure in controlled production of marine shellfish seafoods. In common with clams, oysters, mussels and other species of scallops, the purple-hinge rock scallop is a filter-feeder, deriving its nutrition from the phytoplankton and thus feeds close to the base of the food chain. Bivalves in general occupy the first level of consumers. Our harvest of marine protein one step above the primary producers is ecologically, energetically and economically sound. The rock scallop presents advantages to the seafood culturist on several fronts. The broad natural range of Crassadoma from Alaska to southern Baja California, Mexico, and its habitat from coastal bays to deep water offshore reefs indicates its comparably broad tolerance to environmental conditions. As this guide will show, the rock scallop may be cultivated in both protected and not so protected oceanic waters. Few species of scallops abandon the free-living life style commonly characterizing these shellfish to attach, and in fact cement themselves, to rock or other firm substratum material. Indeed, rock scallops enjoy a free-living juvenile life lasting about six months before cementing by deposition of shell material to an accepted surface. This behavior allows the rock scallop culturist to regulate the spatial distribution to maximize growth potential and minimize the effects of crowding. To this end, a grow-out panel was developed on which young scallops are held at 1/dm2 (ca. 4/ft2). |
Reaching maturity ready for harvest the rock scallops are 10-12 cm (4-5 in.) yet are not crowded to compete for food, oxygen, and living space. Many alternatives exist for scallop grow-out, but frequently crowded scallops cement to one another. Cementation to netting or meshing of containment structures creates difficulties at harvest. Other approaches to grow-out have included glueing individual juvenile scallops to rearing surface materials, allowing the scallops to cement with growth to secure their positions.  Juvenile rock scallops approximately six months old. During this stage, young rock scallops are able to swim briefly and readily attach to surfaces with byssal fibers. Cementation occurs within the next few months.
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